Flat panel displays are used to present visual information to the user. Such displays may be used for example on notebook computers. LCD panels have been used in the past. A more recent flat panel design is the field emission display. Field emission display units include two panels of glass with a vacuum compartment between them containing a number of components. One panel of glass is the anode, which has a phosphor layer, and the other is the cathode. The application of a voltage at discrete control gates between the panels causes an electron flow that causes a portion of the phosphor layer to glow as desired. To manufacture such displays, the two pieces of glass must be brought together and fused about their end portions.
One technique that has been used for preparing flat panel displays is to fuse the panels using heat in a large, single chamber assembly furnace. Such assembly furnaces have multiple stages within the single chamber and each stage has a different temperature. Because of the occurrence of cracks in a panel caused by internal stresses when uneven and quick heating of the glass panel occurs, the assembly furnaces have the multiple stages to gradually heat the panels. The panels pass through the multiple stages and the temperature is raised at each stage so that at the final stage the temperature is at the desired level. These large, single chamber furnaces may have as many as four or five glass panels in them at any one time.
Different processing steps may occur at each stage in the furnace. For example, at an intermediate stage, an e-beam bombardment may occur, which is a process of preconditioning a panel. If at any processing step within the large, single chamber assembly furnace, there is a failure or contamination, all of the glass panels within the large vacuum cavity may have to be discarded. Additionally, with the large, single chamber assembly for flat panels, the entire chamber may have to be pumped out to create the vacuum that is required by the processing step that needs the greatest vacuum.